Sequential posttranslational modifications program FEN1 degradation during cell-cycle progression

Mol Cell. 2012 Aug 10;47(3):444-56. doi: 10.1016/j.molcel.2012.05.042. Epub 2012 Jun 30.

Abstract

We propose that cell-cycle-dependent timing of FEN1 nuclease activity is essential for cell-cycle progression and the maintenance of genome stability. After DNA replication is complete at the exit point of the S phase, removal of excess FEN1 may be crucial. Here, we report a mechanism that controls the programmed degradation of FEN1 via a sequential cascade of posttranslational modifications. We found that FEN1 phosphorylation stimulated its SUMOylation, which in turn stimulated its ubiquitination and ultimately led to its degradation via the proteasome pathway. Mutations or inhibitors that blocked the modification at any step in this pathway suppressed FEN1 degradation. Critically, the presence of SUMOylation- or ubiquitination-defective, nondegradable FEN1 mutant protein caused accumulation of Cyclin B, delays in the G1 and G2/M phases, and polyploidy. These findings may represent a newly identified regulatory mechanism used by cells to ensure precise cell-cycle progression and to prevent transformation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle / physiology*
  • Cell Division / physiology
  • DNA Repair Enzymes / metabolism
  • Flap Endonucleases / genetics*
  • Flap Endonucleases / metabolism*
  • G1 Phase / physiology
  • G2 Phase / physiology
  • Genomic Instability / physiology*
  • Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) / physiology
  • HeLa Cells
  • Humans
  • Nuclear Proteins / metabolism
  • Proteasome Endopeptidase Complex / physiology
  • Protein Processing, Post-Translational / physiology*
  • RNA Splicing Factors
  • S Phase / physiology
  • Sumoylation / physiology
  • Ubiquitin-Activating Enzymes / metabolism
  • Ubiquitin-Conjugating Enzymes / metabolism
  • Ubiquitination / physiology
  • Ubiquitins / metabolism

Substances

  • Nuclear Proteins
  • RNA Splicing Factors
  • SUMO3 protein, human
  • UBA1 protein, human
  • Ubiquitins
  • Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating)
  • Ubiquitin-Conjugating Enzymes
  • Flap Endonucleases
  • FEN1 protein, human
  • Proteasome Endopeptidase Complex
  • Ubiquitin-Activating Enzymes
  • DNA Repair Enzymes
  • PRPF19 protein, human